The official word: DURHAM, N.C. -- When the 3-D version of the 1997 blockbuster film "Titanic" is rereleased in theaters April 4, expect to see First Officer William Murdoch shooting two men and committing suicide by gunshot.

But in reality, surviving crew members said Murdoch was last seen trying to launch lifeboats and is believed to have died in the water.

Hollywood has long spiced up historical films with inaccuracies to make them more entertaining. But when teachers use popular movies in class that play loose with the facts, it can hurt students' ability to separate truth from fiction, according to a Duke University study.

The researchers found that asking students to look for historical errors can backfire, and they can end up learning and remembering inaccurate details alongside the accurate.

"These films represent a double-edged sword because students will often remember whatever information is in them, regardless of whether it is true or false,” said Andrew Butler, a postdoctoral researcher in Duke's psychology department and co-author of the study.

For the research, 36 Duke undergraduates examined nine texts of 800 words each about a historical event or figure. They also watched nine five-minute clips from corresponding major motion pictures.

The students detected only 35 percent of the inaccuracies presented by the films. And those who were asked to detect the inaccuracies in the films learned just as much incorrect information as students who were merely told to watch them.

The historical inaccuracies in movies used in the research included:

-- The film "Glory," which tells the story of the 54th Massachusetts Infantry in the Civil War. Most of the individuals depicted in the film were former slaves from the South. However, most of the recruits in the regiment were actually freemen from Massachusetts and other Northern states.

-- The film "Amadeus" presented Mozart as being a childish and vulgar person. However, there is no evidence that Mozart behaved this way in public. On the contrary, Mozart is thought to have displayed impeccable manners in the presence of royalty and acted professionally with colleagues.

“Unfortunately, students aren’t very good at catching the major historical inaccuracies in popular films, even when explicitly asked to do so,” said Sharda Umanath, a doctoral student in Duke's psychology department and lead author of the study. “The difficulty of detecting the errors makes informing students about what exactly the inaccuracies are in a film absolutely vital to the learning process.”

She said the key to ensuring that students learned correct information is for teachers to provide feedback after students attempted to detect the major historical errors. Then, they learned more correct information and almost no inaccuracies, the authors said.

Students also learned correct information better when they were more interested in the historical texts and movies, the study found.

The study, "Positive and Negative Effects of Monitoring Popular Films for Historical Inaccuracies," will appear in the July/August print edition of Applied Cognitive Psychology. The study posted online in January.